Computer simulated benchmarks of synthetic aperture techniques for vascular ultrasonography

Ultrasound investigations and related techniques strongly depend on the imaged structure: in particular our attention is focused on vascular ultrasound imaging. In this work a high-resolution imaging technique for vascular ultrasound diagnosis has been developed, with emphasis on the investigation of the carotid vessel. This application is relevant due to the stroke risk factor associated with pathological situations. Our study envisages the possibility of more accurate measurements of the lesion's extent by the application of a synthetic aperture imaging technique. An imaging system based on a standard linear array of ultrasonic transducers has been simulated, exploiting the signal acquisition from multi-offset transducers. The synthetic images are quantitatively compared with in vitro carotid ultrasound real images, obtained with a high resolution B-mode scanner. By an experimental procedure the actual transverse carotid sections have been obtained and the digitized video camera profiles have been used to compute the backscattered field under the weak scattering assumption. The set of synthetic radiofrequency signals has been utilized for the reconstruction of synthetic aperture images and B-mode images as well. Finally the effects due to ultrasound propagation and instrumentation characteristics have been discussed and the implications on the image quality and the carotid contour determination have been analysed.